XCOM for z/OS 12.0 uses TYPE=CONFIG members and a compiled Table is no longer supported.
When you specify such a compiled table in a XCOM Job running under 12.0 XCOM creates a TYPE=CONFIG-member in the XCOMCNTL-Dataset. This is indicated by message XCOMM1423I in the Job Output:
XCOMM1460I Symbol CONFIGDSN=XCOMCNTL
XCOMM1461I Searching XCOMCNTL for TYPE=CONFIG member ABCDEF
XCOMM0265E <table> MEMBER NOT FOUND IN PDS DATASET
XCOMM0763I DEFAULT TABLE <table> LOADED. GENERATED 20130806 AT 05.17
XCOMM1423I <table> CONFIG MEMBER BEING CREATED FROM DEFAULT TABLE <table> GENERATED yyymmdd AT hh.tt